Information distribution systems, such as cable and satellite television systems, including transmission stations and reception stations have become so prevalent that most consumers take them for granted. The wide bandwidth available in some digital information distribution systems allows content providers to provide viewers with vast amounts of programming content. For example, while past conventional analog cable television systems provided viewers with tens of channels, modern satellite television systems, such as, for example, the DIRECTV® system provides viewers with literally hundreds of choices of programming content. As a further example, while analog cable systems provided viewers with one HBO channel, modern digital systems provide viewers with as many as six HBO channels, each of which includes different program content.
System operators who are quality-minded monitor the information that is broadcast over their systems to ensure that broadcast audio and video quality are acceptable. For example, concerned system operators may monitor video for the presence of quality issues such as video freeze (a situation in which video information provided to viewers appears frozen), video blackout (a situation in which black video, rather than desired visual content, is being broadcast to viewers) and/or audio silence that is not a desirable part of the programming. The presence of any one of these quality issues causes concerned system operators to scramble to fix the outgoing programming quality provided to users.
Traditionally, because analog cable systems provided relatively few channels of content (e.g., 50 channels), system operators could hire personnel to watch each channel of programming, thereby monitoring quality. Employees would view as many as four channels simultaneously, while watching for the occurrence of video freeze, video blackout or audio silence. As can be readily appreciated, human monitoring of broadcast content was expensive and prone to error, yet it was possible and not economically prohibitive due, in large part, to the few channels being monitored.
The explosion in programming content broadcast by a single provider, as noted above, now means that providers using digital distribution systems are transmitting as many as 800 channels of audio and video. System operators that are still concerned with the quality of broadcast content largely rely on two monitoring techniques: human monitoring and automated monitoring of baseband signals, each of which is described below.
As noted previously, humans watching program content may be asked to make subjective assessments regarding the quality of transmission. For example, humans can watch channels of content waiting for the occurrence of a video freeze, a video blackout or audio silence. Again, human labor is expensive, especially given the need to monitor as many as 800 channels of content. To minimize the number of humans needed to monitor video signals, monitor walls displaying multiple channels of content are used. However, the effectiveness of such an approach is inversely proportional to the number of channels simultaneously monitored, due to the limitations of the human viewers. Additionally, humans cannot reliably listen to numerous audio sources in parallel, therefore audio signals need to be monitored in sequence, which significantly increases the time and manpower required to detect silent audio or audio outages. In addition to the human factors associated with monitoring transmission content, a substantial quantity of hardware is required to facilitate the monitoring. For example, a monitoring installation must include a number of video displays and decoder banks because each encoded signal must be decoded and displayed to the viewers. The result can be as many as 800 decoders, which contributes significant expense to the monitoring operation.
As an alternative to human monitoring of transmissions, automated monitoring has been used. Automated monitoring systems process baseband video and audio signals (i.e., audio and video signals that are uncompressed or decoded) in search of signal quality issues. Automated monitoring, like human monitoring, has been traditionally performed on decoded signals, therefore decoders are required for each channel that is to be monitored, again resulting in the need for as many as 800 decoders. To reduce the number of decoders that are required, system operators may use decoders in a sequential manner, scanning one channel after another. However, using decoders in a sequential manner extends the time it takes for the monitoring system to detect frozen or blacked out video or silent audio. In addition to the oppressive cost of the numerous decoders, the cost of the monitoring equipment that analyzes the output from the decoders is significant.